Specifying Immediate-Leave Host Removal for MLD

The immediate leave setting is useful for minimizing the leave latency of MLD memberships when only one receiver host is connected to each interface. The routing device removes the host from the multicast group as soon as the routing device receives a leave group message from the host associated with the interface.

Use the immediate leave setting on MLD interfaces to which only one MLD host is connected. If more than one MLD host is connected to a LAN through the same interface, and one host sends a done message, the router removes all hosts on the interface from the multicast group. The router loses contact with the hosts that properly remain in the multicast group until they send join requests in response to the router’s next general multicast listener query.

When this statement is enabled on a router running MLDv1, after the router receives a multicast listener done message from a host associated with the interface, the router immediately removes the group membership from the interface and suppresses the sending of any group-specific queries for the multicast group.

When this statement is enabled on a router running MLDv2, after the router receives a report with the type BLOCK_OLD_SOURCES, the router suppresses the sending of group-and-source queries but relies on the Junos OS-supported host tracking mechanism to determine whether or not it removes a particular source group membership from the interface.

When immediate leave is disabled and one host sends a leave group message, the routing device first sends a group query to determine if another receiver responds; if no other receivers respond, the routing device removes all hosts on the interface from the multicast group. Immediate leave is disabled by default.

To enable immediate leave:

1. Configure immediate leave on the MLD interface.
   [edit]user@host# edit protocols mlduser@host# set interface ge-0/0/0.1 immediate-leave
2. Verify the configuration by checking the Immediate Leave field in the output of the show mld interface command.

Related Topics

• MLD Overview
• show mld interface in the Routing Protocols and Policies Command Reference